Mercury-based traditional herbo-metallic preparations: a toxicological perspective

Abstract

This review aims to explore the toxicological aspects of mercury-based herbo-metallic preparations like cinnabar and "Rasasindura" that are primarily composed of mercuric sulfide (HgS). Cinnabar-containing preparations have been used extensively in Indian and Chinese systems of medicine for treatment of chronic ailments like syphilis, high fever, pneumonia, insomnia, nervous disorders, deafness, and paralysis of the tongue. Contrary to Western medicine, which does not promote the use of mercury due to its toxic effects, Indian and Chinese traditional practitioners believe that mercury-based formulations have potent therapeutic efficacy, while there is no toxicity due to the unique and repeated purification processes employed during preparation. However, lack of proper pharmacovigilance and widespread self-medication has resulted in undesirable effects to certain sections of the consumers of these preparations, which have contributed to the negative publicity for these forms of medicine. Variations in the quality of the preparations coupled with the lack of understanding of the differences in the recommended dosages and treatment strategies adopted by traditional medicine practitioners, further fuels concerns in the Western world on the safety and efficacy of traditional medicine. But in spite of these concerns, concerted efforts to understand the biological interactions and transformations of these preparations are yet to gain momentum. Although scattered reports on the toxicity of these preparations are available in literature, their mechanism of action has not been conclusively established. Long-term pharmacotherapeutic and in-depth toxicity studies are needed to address the apprehensions raised by these herbo-metallic preparations. This review highlights the lacunae in the studies conducted thus far, and assesses the need for further studies to provide significant data to establish the safety and efficacy of such preparations, as well as develop gold standards for stringent quality control of these preparations.

Developmental toxicity from exposure to various forms of mercury compounds in medaka fish (Oryzias latipes) embryos

“…Mercury-based herbo-metallic preparations have been used in traditional medicines for thousands of years (Kamath et al, 2012) and continue to see usage today. Currently, the Pharmacopeia of China has 26 recipes that contain cinnabar ( α -HgS).…”

“…For centuries, mercury has been used as an ingredient in diuretics, antiseptics, skin ointments and laxatives, and more recently, as a dental amalgam and as a preservative in some vaccines (Clarkson, Magos & Myers, 2003; Liu et al, 2008). In traditional Indian Ayurvedic (Kamath et al, 2012), Chinese (Pharmacopeia of China, 2015) and Tibetan medicines (Chen et al, 2012; Kan, 2013; Li et al, 2014; Wu et al, 2016), mercuric sulfides are frequently included in the treatment of various disorders, with the result that health concerns for public safety are increasing (Liu et al, 2008; Kamath et al, 2012). This form of mercury, from the naturally occurring minerals, cinnabar and metacinnabar, typically undergoes purification and preparation prior to use (Kamath et al, 2012; Li et al, 2016).…”

“…In traditional Indian Ayurvedic (Kamath et al, 2012), Chinese (Pharmacopeia of China, 2015) and Tibetan medicines (Chen et al, 2012; Kan, 2013; Li et al, 2014; Wu et al, 2016), mercuric sulfides are frequently included in the treatment of various disorders, with the result that health concerns for public safety are increasing (Liu et al, 2008; Kamath et al, 2012). This form of mercury, from the naturally occurring minerals, cinnabar and metacinnabar, typically undergoes purification and preparation prior to use (Kamath et al, 2012; Li et al, 2016). Zuotai is primarily composed of β -HgS (metacinnabar) while cinnabar ( Zhu Sha ) is α -HgS (Li et al, 2016; Wu et al, 2016).…”

“…However, these doses can be considerably higher than what is considered to be safe in Western countries (Liu et al, 2008) (see Table S1). Inorganic mercury chloride (HgCl 2 ) and organic methylmercury (MeHg) forms are highly toxic and never used in these treatments (Kamath et al, 2012). This distinction is important because it is the total mercury content rather than specific chemical forms that are commonly used to assess risk of traditional medicines, and this approach may be inaccurate.…”

Arsenic: an ancient toxicant of continuous public health impact, from Iceman Ötzi until now

“…• Heavy metals, including arsenic, are being used in traditional medicines in Asia, which is being addressed as a major toxicological problem, for instance in China and India (Liu et al 2008;Kamath et al 2012). Recently, arsenic trioxide is being recommended for a very special medicinal use, that is, in the treatment for acute promyelocytic leukaemia (Emadi and Gore 2010).…”